ABSTRACT
In a 2005 feasibility study, the U.S. Departments of Energy and Agriculture predicted that within four decades, the United States could sustainably produce over 1 billion dry tons of plant biomass annually for the generation of energy and other products (DOE and USDA 2005). Crop and other residues from grasses, including 256 million tons of corn stover and 52 million tons of wheat straw, represent approximately 348 million tons of this total. An additional 368 million tons is expected to come from the cultivation of perennial grasses and trees as dedicated bioenergy crops (DOE and USDA 2005). Switchgrass (Panicum virgatum) and Miscanthus (Miscanthus × giganteus) have emerged as particularly attractive potential energy crops (DOE 2007; Dohleman and Long 2009). Given that the grasses being considered as energy crops are essentially undomesticated wild selections, there is considerable potential for improving them. In addition, with the exception of forest trees, many of the traits desirable in an energy crop (e.g., thicker stems, more cell walls) have not been selected for in traditional crops, in which, for the most part, breeding has focused on reproductive organs or digestible leaves, tubers, or stems. Unfortunately, breeding the grasses proposed as energy crops is complicated by their reproductive strategy (self-incompatibility or sterility) which prevents the development of inbred lines, selng, etc. Basic research on the biology of grasses could be used to design rational approaches to breeding superior energy crops and to accelerate the domestication of these new crops. The most rapid way to gain this basic knowledge is through the use of an appropriate model system.
